关于外键注释上同一实体的Hibernate OneToOne关系

Question

我有一个名为Post的实体类。该班级有ParentId的字段。这是相同实体类的Foreign key。

我试过Annotations几种不同的方法，但我总是遇到一些错误。例如。

org.hibernate.MappingException: Could not determine type for: dk.nwessel.model.Post, at table: Posts, for columns: [org.hibernate.mapping.Column(post)] 

我的代码：

@Entity 
@Table(name = "Posts", catalog = "StackOverflow") 

public class Post { 
    private Integer Id, PostTypeId, ParentId, AcceptedAnswerId, Score, ViewCount, OwnerUserId, LastEditorUserId, AnswerCount, 
      CommentCount, FavoriteCount; 
    private String Body, Title, Tags; 
    private Date CreationDate, LastEditDate, LastActivityDate; 

    @OneToOne(cascade = CascadeType.ALL) 
    @JoinColumn(name = "ParentId") 
    private Post post; 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    @Column(name = "Id", unique = true, nullable = false) 
    public Integer getId() { 
     return Id; 
    } 

    public void setId(Integer id) { 
     Id = id; 
    } 

    @Column(name = "PostTypeId") 
    public Integer getPostTypeId() { 
     return PostTypeId; 
    } 

    public void setPostTypeId(Integer postTypeId) { 
     PostTypeId = postTypeId; 
    } 


    public Post getPost(){ 
     return post; 
    } 

    @Column(name = "ParentId") 
    public Integer getParentId() { 
     return ParentId; 
    } 

    public void setParentId(Integer parentId) { 
     ParentId = parentId; 
    } 

    @Column(name = "AcceptedAnswerId") 
    public Integer getAcceptedAnswerId() { 
     return AcceptedAnswerId; 
    } 

    public void setAcceptedAnswerId(Integer acceptedAnswerId) { 
     AcceptedAnswerId = acceptedAnswerId; 
    } 

    @Column(name = "Score") 
    public Integer getScore() { 
     return Score; 
    } 

    public void setScore(Integer score) { 
     Score = score; 
    } 
    @Column(name = "ViewCount") 
    public Integer getViewCount() { 
     return ViewCount; 
    } 

    public void setViewCount(Integer viewCount) { 
     ViewCount = viewCount; 
    } 
    @Column(name = "OwnerUserId") 
    public Integer getOwnerUserId() { 
     return OwnerUserId; 
    } 

    public void setOwnerUserId(Integer ownerUserId) { 
     OwnerUserId = ownerUserId; 
    } 
    @Column(name = "LastEditorUserId") 
    public Integer getLastEditorUserId() { 
     return LastEditorUserId; 
    } 

    public void setLastEditorUserId(Integer lastEditorUserId) { 
     LastEditorUserId = lastEditorUserId; 
    } 
    @Column(name = "AnswerCount") 
    public Integer getAnswerCount() { 
     return AnswerCount; 
    } 

    public void setAnswerCount(Integer answerCount) { 
     AnswerCount = answerCount; 
    } 
    @Column(name = "CommentCount") 
    public Integer getCommentCount() { 
     return CommentCount; 
    } 

    public void setCommentCount(Integer commentCount) { 
     CommentCount = commentCount; 
    } 
    @Column(name = "FavoriteCount") 
    public Integer getFavoriteCount() { 
     return FavoriteCount; 
    } 

    public void setFavoriteCount(Integer favoriteCount) { 
     FavoriteCount = favoriteCount; 
    } 
    @Column(name = "Body") 
    public String getBody() { 
     return Body; 
    } 

    public void setBody(String body) { 
     Body = body; 
    } 
    @Column(name = "Title") 
    public String getTitle() { 
     return Title; 
    } 

    public void setTitle(String title) { 
     Title = title; 
    } 
    @Column(name = "Tags") 
    public String getTags() { 
     return Tags; 
    } 

    public void setTags(String tags) { 
     Tags = tags; 
    } 

    @Temporal(TemporalType.DATE) 
    @Column(name = "CreationDate") 
    public Date getCreationDate() { 
     return CreationDate; 
    } 

    public void setCreationDate(Date creationDate) { 
     CreationDate = creationDate; 
    } 

    @Temporal(TemporalType.DATE) 
    @Column(name = "LastEditDate") 
    public Date getLastEditDate() { 
     return LastEditDate; 
    } 

    public void setLastEditDate(Date lastEditDate) { 
     LastEditDate = lastEditDate; 
    } 

    @Temporal(TemporalType.DATE) 
    @Column(name = "LastActivityDate") 
    public Date getLastActivityDate() { 
     return LastActivityDate; 
    } 

    public void setLastActivityDate(Date lastActivityDate) { 
     LastActivityDate = lastActivityDate; 
    } 

} 

Answer 1

您还需要引用其中的ParentId指向：

@JoinColumn(name = "ParentId", referencedColumnName = "Id") 

编辑：我也看到的ParentId不是唯一的。这将使你的关系@ManyToOne而不是@OneToOne